Gel electrophoresis of maternal and fetal serum cholinesterases from normal pregnancies and of those affected by neural tube defects.

The cholinesterase isozymes of maternal and fetal sera from normal pregnancies and those in which the fetus had a neural tube defect were studied using flat-bed vertical polyacrylamide gel electrophoresis. Normal maternal and fetal sera had multiple bands of cholinesterase activity, including the two bands in the position of those found in amniotic fluid from NTD pregnancies. The one difference between maternal and fetal sera was that the faster of these two "amniotic fluid bands" was acetylcholinesterase in fetal serum, as in the neural tube defect amniotic fluids, but non-specific cholinesterase in maternal serum. In artificial mixtures this difference could be used to differentiate between maternal and fetal blood-contamination of amniotic fluids, but in samples naturally contaminated at amniocentesis this test did not always agree with the Kleihauer findings. Both maternal and fetal sera had additional weak acetylcholinesterase activity in the most anodally migrating enzyme bands, but all other enzyme activity was non-specific cholinesterase. No difference was observed in the isozymes of fetal serum from normal fetuses and those with neural tube defects, or of maternal serum from normal and neural tube defect pregnancies.